How do I work with the site guest user?

Salesforce has recently introduced stricter security controls for guest users, including explicit sharing and permissions for guest users to access certain data. Permission sets and profiles give users access to objects and fields, and sharing rules give users access to records. Admins must consider both when using Campaign Monitor for Salesforce with a guest user.

Object and field Access

When you assign our Guest Permission Set, the guest user can access the objects and fields that make up our product, like subscriber lists and mailing campaigns. You must also ensure the guest user can access the object and relevant fields if you work with leads, contacts, or person accounts. The same is true if you are referencing other objects' fields--via lookups or formulas, for instance. 

In Campaign Monitor for Salesforce, that access may be needed so that the guest user can create contacts and leads, map fields to Campaign Monitor custom fields, or send transactional emails.

Record Access

Sharing rules must be configured to specify which records a guest user can access.

For Transactional Email, sharing rules must allow access to the Smart Email object and its records.
For Field Mappings sharing rules must allow access to the Custom Field Mapping object and its records.
For Subscriber Rules sharing rules must allow access to the Automatic subscription object and its records.

If you use Contact records, please ensure each Contact is associated with an Account. Contacts are controlled by their parent Account—without this relationship, access may fail. The same is true of any child object controlled by a parent object in Sharing Settings.

Below is a video on how to set up the site guest user to work with transactional emails. To learn about visibility and access in Salesforce, see the Who Sees What video series, Salesforce documentation, or Trailhead.